Multipolar permanent magnetic brake



Nov. 6, 1962 M. F. REYNST MULTIPOLAR PERMANENT MAGNETIC BRAKE Filed Oct. 12, 1959 FIG 2 INVENTOR maximilien felix reynst United rates Patent 3,062,977 MULTIPOLAR PERMANENT MAGNETIC BRAKE Maximilien Felix Reynst, Eindhoven, Netherlands, as-

signor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Oct. 12, 1959, Ser. No. 845,907 Claims priority, application Netherlands Oct. 11, 1958 2 Claims. (Cl. 310-93) This invention relates to a multipolar magnetic brake operating on the eddy current principle, for vehicles, in particular for motor-cars, at least one part, in which the eddy currents are set up, being arranged coaxially about at least one magnet structure, and the parts of the magnet structure having relative rotation.

Care must be taken to ensure that the parts in which the eddy currents are set up, are intensively cooled, since the energy to be dissipated is completely converted into heat. The greater the power of the brake, the more heat must be conducted away. It is already known to provide the rotor of a similar brake with ventilator vanes in order to obtain a forced air stream for cooling. These ventilator vanes are mounted on the part in which the eddy currents are set up, so that they serve also as cooling fins. However, the requirements to be satisfied by ventilator vanes and cooling fins differ from one another, so that for the combination, in general a compromise, must be chosen so that either the cooling effect or the ventilator effect remains below the possible optimum.

It is an object of the present invention to provide a construction in which the requirements of cooling and of ventilation are completely matched.

According to the presently preferred form of the invention, the magnet structure is provided with ventilator vanes which are arranged axially adjacent the magnet structure, the part in which the eddy currents are set up, being provided with cooling fins, while axially adjacent the part in which the eddy currents are set up, at least one closing member is disposed, which overlaps this part and by which the cooling fluid is directed axially past the cooling fins.

Both the cooling fins for the part or parts in which the eddy currents are set up and the ventilator vanes can be chosen entirely independently with respect to their numher, position and shape, so that the maximum cooling efficiency is obtainable. The closing members ensure that the cooling fluid is directed in the correct direction past the cooling fins.

According to a further feature of the invention, a number of magnet structures and co-operating parts are arranged adjacent axially and axially displaceable relatively to one another, the spacing between the parts in which the eddy currents are set up being substantially equal to the width of a magnet structure.

The braking power is controlled by the axial displacement of the magnet structures relative to the parts in which the eddy currents are set up. Thus, the ventilator power is adjusted at the same time, since the open space between the parts in which the eddy currents are set up, is closed to a greater or lesser extent by the permanent magnet structure. When the brake is switched ofi, that is to say, when the permanent magnet structures are dis posed at the sides of the parts in which the eddy currents are set up, the ventilator is substantially shut oif, since the permanent magnet structures lie opposite the apertures between the parts in which the eddy currents are set up. Thus, the continuously rotating rotor is prevented ice 2 from taking the full ventilator power from the source of energy if the brake is switched off.

Preferably, the parts in which the eddy currents are set up, are arranged to surround the magnet structures, and the ventilator vanes are disposed between the magnet structures, while the closing members are provided around the outer diameter of the cooling fins between the parts in which the eddy currents are set up.

In order that the invention may readily be carried out, an embodiment thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which FIGURE 1 is an axial sectional view of a brake in accordance with the invention, and

FIGURE 2 is a sectional view taken along the line II-II of FIGURE 1.

Permanent magnet structures 2 and 3, which are built similarly to those described in co-pending patent application No. 764,147 filed September 29, 1958, are mounted on a shaft 1. These permanent structures co-operate with parts 4 and 5, which are arranged in a housing 6 mounted on the shaft 1. The said parts are copper cylinders which engage iron rings 8 provided with cooling fins 7. The width of the cooling fins exceeds the width of the magnet structures 2 and 3. The shaft 1 can be connected to the wheels of the vehicle so as to be rotated. Ventilator vanes 9 are disposed on both sides of each magnet structure 2 and 3. Closing member 10 spaced from the parts 4 and 5 by fins 7 ensure that the cooling fluid is axially directed past the cooling fins '7 in a direction shown by the arrows. A displacement of the permanent magnet structures 2 and 3, or of the parts 4 and 5 (housing 6), along the axis of the shaft 1 not only ensures that the brake is switched Oh, but also that the ventilator is shut off to a greater or lesser extent. For this purpose, theventilator vanes disposed at the outer sides of the outer magnet structures, are provided with a protruding rim 11. when the brake is completely switched off, the permanent magnet constructions are arranged precisely opposite the open spaces between parts 4 and 5 in which the eddy currents are set up, so that they substantially close the path to be taken by the cooling fluid.

What is claimed is: a

1. An eddy current machine comprising a shaft, at least two spaced magnetic means secured on said shaft, a plurality of blower means secured on said shaft sandwiching said magnetic means therebetween, radially spaced concentric eddy current generator means operatively associated with said magnetic means, heat dissipation means secured to said generator means including a plurality of cooling fins, whereby fluid channels are defined completely surrounding said eddy current generator means, and a perforated housing member supporting said generator means and associated dissipation means, said housing member supported on said shaft for relative axial movement therebetween.

2. A machine according to claim 1 with the addition of radially extending ring means secured to the axially extreme ends of said blower means.

References Cited in the file of this patent UNITED STATES PATENTS 2,827,581 Hayes Mar. 8, 1958 2,908,834 Munson Oct. 13, 1959 FOREIGN PATENTS 1,132,712 France Nov. 5, 1956 

